import java.io.*;
import java.util.*;
import java.text.*;
import java.math.*;
import java.util.regex.*;

public class Solution {

    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        int n = in.nextInt();
        int[][] arr=new int[n][n];
        for(int a0 = 0; a0 < n; a0++){
            int x = in.nextInt();
            int y = in.nextInt();
            arr[a0][0]=x;
            arr[a0][1]=y;
        }
        int flag=1;
        for(int i=0;i<n-1;i++)
            {
            if(arr[i][0]!=arr[i+1][0] && arr[i][1]!=arr[i+1][1])
                {
                flag=0;break;
            }               
        }
       String ans=(flag==1)?"YES":"NO";
        System.out.println(ans);
    }
}